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In chemistry, the term "turnover number" has two distinct meanings.. In enzymology, the turnover number (k cat) is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration [E T] for enzymes with two or more active sites. [1]
To address such a paradox, Kuo-Chen Chou and his co-workers proposed a model by taking into account the spatial factor and force field factor between the enzyme and its substrate and found that the upper limit could reach 10 10 M −1 s −1, [6] [7] [8] and can be used to explain some surprisingly high reaction rates in molecular biology. [5 ...
The Lineweaver–Burk plot derives from a transformation of the Michaelis–Menten equation, = + in which the rate is a function of the substrate concentration and two parameters , the limiting rate, and , the Michaelis constant.
When a non-competitive inhibitor is added the Vmax is changed, while the Km remains unchanged. According to the Lineweaver-Burk plot the Vmax is reduced during the addition of a non-competitive inhibitor, which is shown in the plot by a change in both the slope and y-intercept when a non-competitive inhibitor is added. [8]
The main difference between ribozymes and enzymes is that RNA catalysts are composed of nucleotides, whereas enzymes are composed of amino acids. Ribozymes also perform a more limited set of reactions, although their reaction mechanisms and kinetics can be analysed and classified by the same methods.
Although the enzyme kinetics (unimolecular rate constant (kcat), Km and kcat/km) of the two enzymes were not significantly different, human PARP-1 was found to have a two-fold higher specific automodification capacity than the rat enzyme, which the authors posited could account, in part, for the higher PARP activity in humans than rats. [12]
An active site titration process can be done for the elimination of errors arising from differences in cultivation batches and/or misfolded enzyme and similar issues. This is a measure of the amount of active enzyme, calculated by e.g. titrating the amount of active sites present by employing an irreversible inhibitor.
In the field of biochemistry, the specificity constant (also called kinetic efficiency or /), is a measure of how efficiently an enzyme converts substrates into products.A comparison of specificity constants can also be used as a measure of the preference of an enzyme for different substrates (i.e., substrate specificity).